The present invention relates to a dust collection apparatus having a packed tower and, more particularly, to a dust collection apparatus for cleaning an exhaust gas containing a noxious material of semiconductor devices or dust by using a filter.
FIG. 3 shows an example of a conventional dust collection apparatus having a packed tower. Conventionally, as shown in FIG. 3, a dust collection apparatus of this type has a tower main body 20, a filter 4, a demister 5, a circulating pump 7, supply nozzles 8, and an oblique plate 3. The tower main body 20 has a suction port 1 and an exhaust port 2 through which the exhaust gas is taken and exhausted, respectively. The filter 4 is accommodated in the tower main body 20 to separate the noxious material. The demister 5 removes the water content from the exhaust gas to be exhausted through the exhaust port 2. The circulating pump 7 circulates a cleaning solution 6 reserved in the lower portion of the tower main body 20. The supply nozzles 8 supply the cleaning solution 6 to the filter 4. The oblique plate 3 guides the exhaust gas so as to flow toward the filter 4 in the tower main body 20.
A supply valve 10, a supply port 9, a discharge valve 12, and a discharge port 11 are formed along the circulation line of the cleaning solution 6. The cleaning solution 6 is periodically exchanged to prevent it from deterioration.
The operation of the conventional dust collection apparatus having the above arrangement will be described. First, the exhaust gas containing a noxious gas or dust is fed into the tower main body 20 of the packed tower through the suction port 1. The exhaust gas fed through the suction port 1 is straightened toward the filter 4 by the oblique plate 3 so that it will not form a turbulent flow in the tower main body 20. The cleaning solution 6 sprayed from the supply nozzles 8 arranged above the filter 4 forms a solution film on the surface of the packing of the filter 4 and causes direct inertial collision with the exhaust gas. Cleaning and dust collection are performed through diffusion and attachment of the fine particles of the exhaust gas. Thereafter, the water content is removed by the demister 5 arranged in the later stage, and the cleaned exhaust gas is discharged through the exhaust port 2.
The cleaning solution 6 is circulated in the packed tower by the circulating pump 7 and is adjusted such that its amount in the packed tower is constant. In order to prevent deterioration of the cleaning solution 6 the discharge valve 12 is periodically opened and the cleaning solution 6 is discharged through the discharge port 11. The supply valve 10 is opened and the cleaning solution 6 is replenished by an amount corresponding to the amount discharged through the supply port 9, so that the amount of the cleaning solution 6 in the tower main body 20 is constant.
The first problem of the conventional dust collection apparatus is as follows. In the conventional dust collection apparatus described above, when the apparatus is installed in a semiconductor manufacturing factory that manufactures semiconductor devices 24 hours a day, operation must be performed with the risk of a high pressure loss. In this conventional packed tower type dust collection apparatus, in order to clean off the dust and reaction product attaching to the filter 4, the filter 4 must be extracted from the tower main body, cleaned, and packed in the tower main body again. This requires much labor and time. Therefore, in the factory that manufactures semiconductor devices 24 hours a day, the filter 4 can be cleaned only periodically, and the operation is performed with the dust and reaction product attaching to the filter 4.